I wouldn't use coconut flour (because the moisture content of the batter would be way off) but you could try substituting with ground pumpkin seeds! (fedandfit.com)
Lately, I've been experimenting with adding ground pumpkin seeds in place of some flours in baked goods, and I'm really loving the results. (golubkakitchen.com)
I used half cup flax meal and half cup ground pumpkin seeds. (101cookbooks.com)